A volcano in a mug. Neat idea to show kids how they work. Much more accurate than the old baking soda/vinegar idea.
teach the water cycle to children with this water cycle craft --- a water cycle windsock
Water Cycle - Magic School Bus. We watched this one today, and it really connected some dots for Nugget. If you enjoy the show, buy the boxed set on DVD. One of our best resources for fun leaping-off points for learning.
SC.5.E.7.1 Create a model to explain the parts of the water cycle. Water can be a gas, a liquid, or a solid and can go back and forth from one state to another. Amazon.com: Water Cycle Wheel Science Kit (makes 25 projects): Toys & Games